A full-tab cylindrical lithium-ion battery and an electric device

Abstract

The application relates to the technical field of lithium ion batteries, and discloses a full-tab cylindrical lithium ion battery, wherein the positive active material in the positive electrode active material coating is LiNi x Co y Mn z M j O2, wherein the value range of x is 0.8-0.95, the value range of y is 0.01-0.1, the value range of z is 0.01-0.1, the value range of j is 0-0.05, x+y+z+j=1, M comprises one or more of aluminum Al, zirconium Zr, titanium Ti, magnesium Mg, strontium Sr, yttrium Y, lanthanum La, cerium Ce and vanadium V; the nominal capacity is 3.0 Ah-5.5 Ah, the nominal voltage is 3.5 V-3.7 V; the discharge capacity retention rate when continuously discharging at 8C rate to the cut-off voltage 2.5 V at 25 DEG C is greater than or equal to 80%; and the surface maximum temperature rise in the 8C continuous discharging process is less than or equal to 40 DEG C; the value range of the alternating current internal resistance ACIR at 25 DEG C is 1 m omega-6 m omega, and the value range of the direct current internal resistance DCR is 3 m omega-15 m omega.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, specifically to a multi-tab cylindrical lithium-ion battery and an electrical device. Background Technology

[0002] With the rapid development of fields such as drones, electric vertical takeoff and landing (eVTOL) aircraft, and high-performance power tools, stringent requirements have been placed on the power performance of power batteries. These applications not only require batteries to have a high-rate continuous discharge capability of 8C or higher, but also require batteries to achieve low heat rise under high-rate operating conditions while maintaining stable cycle life.

[0003] Among the mainstream cylindrical lithium-ion battery models currently available, the 18650 battery, limited by its casing diameter, suffers from shortcomings in current carrying capacity and heat dissipation area under high-rate conditions. While the 21700 battery increases capacity by increasing cell volume, its 70mm cell height is not conducive to layout in some compact devices, and the increased cell volume further exacerbates internal heat accumulation during high-rate discharge. The 21650 cell (approximately 21mm in diameter and 65mm in height) can provide a current conduction cross-section comparable to that of the 21700 in the radial direction, and its shorter axial height can reduce the axial current density gradient of the electrodes and shorten the heat dissipation path, making it more suitable for high-power applications from a theoretical perspective.

[0004] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art: Most 21650 batteries in related technologies adopt a traditional single-tab structure, with the tab located only in a small area at the end of the electrode. During high-rate discharge, the current needs to be collected from the entire surface density area of ​​the electrode to the tab, resulting in extremely high current density in the tab area, a surge in ohmic heat and polarization heat, causing the following technical defects: (1) high AC internal resistance (ACIR) and DC internal resistance (DCR), resulting in large energy loss during discharge at 8C and above; (2) significant temperature rise at the tab, limiting the battery's continuous high-power output capability; (3) the tab area is subjected to high current density and high temperature for a long time, accelerating the damage of the SEI film and the decomposition of the electrolyte, leading to a rapid increase in DCR and a decrease in lifespan during cycling.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0007] This disclosure provides a fully tabbed cylindrical lithium-ion battery and an electrical device, which systematically couples and constrains the fully tabbed structural features with multi-dimensional electrical performance parameters to form the core performance boundary of the high-power battery.

[0008] In some embodiments, the all-tab cylindrical lithium-ion battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode is composed of a positive current collector and a positive active material coating applied to at least one surface thereon. The negative electrode is composed of a negative current collector and a negative active material coating applied to at least one surface thereon. The positive active material in the positive active material coating is LiNi. x Co y Mn z M j O2, wherein x ranges from 0.8 to 0.95, y ranges from 0.01 to 0.1, z ranges from 0.01 to 0.1, j ranges from 0 to 0.05, and x+y+z+j=1; M includes one or more of aluminum (Al), zirconium (Zr), titanium (Ti), magnesium (Mg), strontium (Sr), yttrium (Y), lanthanum (La), cerium (Ce), and vanadium (V); the nominal capacity of the all-tab cylindrical lithium-ion battery is 3.0Ah to 5.5Ah. The voltage is 3.5V~3.7V; the discharge capacity retention rate of the all-tab cylindrical lithium-ion battery at 25℃ when continuously discharged at an 8C rate to a cutoff voltage of 2.5V is greater than or equal to 80%; and the maximum surface temperature rise during the 8C continuous discharge process is less than or equal to 40℃; the AC internal resistance ACIR of the all-tab cylindrical lithium-ion battery at 25℃ is in the range of 1mΩ~6mΩ, and the DC internal resistance DCR is in the range of 3mΩ~15mΩ.

[0009] Optionally, the positive electrode current collector is aluminum foil, and the proportion (a1) of the aluminum foil to the total weight of the all-tab cylindrical lithium-ion battery is 3.5 wt% to 5.3 wt%; the proportion (a2) of the positive electrode active material coating to the total weight of the all-tab cylindrical lithium-ion battery is 32.1% to 46.7%; the negative electrode current collector is copper foil, and the proportion (b1) of the copper foil to the total weight of the all-tab cylindrical lithium-ion battery is 6.1 wt% to 13.2 wt%; the proportion (b2) of the negative electrode coating to the total weight of the battery is 17.4% to 27.5%, and satisfies: 0.016 ≤ (a1) b1) / (a2 b2)≤0.157 Optionally, the ratio c1 of the electrolyte to the total weight of the all-tab cylindrical lithium-ion battery is 8.4%~17.3%, and the amount of electrolyte injected satisfies: 1g / Ah~1.6g / Ah.

[0010] Optionally, the all-tab cylindrical lithium-ion battery is continuously discharged at an 8C rate to a cutoff voltage of 2.5V at an ambient temperature of 25°C, and the surface temperature of the battery does not exceed 80°C during the discharge process; the discharge capacity retention rate of the all-tab cylindrical lithium-ion battery when continuously discharged at a 10C rate to a cutoff voltage of 2.5V at 25°C is greater than or equal to 75%.

[0011] Optionally, the voltage drop of the all-tab cylindrical lithium-ion battery is less than or equal to 0.5V when continuously discharged at a 5C rate for 10s at an ambient temperature of -20℃.

[0012] Optionally, the temperature rise coefficient k of the all-tab cylindrical lithium-ion battery is less than or equal to 5°C / C, where k = (T 8C -T 0.2C ) / 8, T 8C T represents the surface temperature of the cell at the end of an 8C discharge. 0.2C The surface temperature of the cell at the end of a 0.2C discharge.

[0013] Optionally, the DC internal resistance (DCR) of the all-tab cylindrical lithium-ion battery at 25°C is 3mΩ~10mΩ; the DC internal resistance (DCR) of the all-tab cylindrical lithium-ion battery at -20°C is 40mΩ~90mΩ; and after 500 cycles at 1C / 1C, the DC internal resistance (DCR) growth rate of the all-tab cylindrical lithium-ion battery at 25°C is less than or equal to 50%.

[0014] Optionally, the maximum continuous discharge current of the all-tab cylindrical lithium-ion battery is greater than or equal to 70A; the maximum pulse discharge current of the all-tab cylindrical lithium-ion battery is greater than or equal to 200A.

[0015] Optionally, the outer diameter of the casing of the all-tab cylindrical lithium-ion battery is 20.8mm~21.5mm, and the height of the casing is 64.8mm~65.5mm.

[0016] In some embodiments, the electrical device includes a multi-tab cylindrical lithium-ion battery as described in this application.

[0017] The fully tabbed cylindrical lithium-ion battery and power-consuming device provided in this disclosure can achieve the following technical effects: By synergistically defining the all-tab structure and electrical performance parameters, the discharge capacity retention rate at 25°C during continuous discharge at an 8C rate to a cutoff voltage of 2.5V is greater than or equal to 80%; and the maximum surface temperature rise during continuous 8C discharge is less than or equal to 40°C. The AC internal resistance (ACIR) of the all-tab cylindrical lithium-ion battery at 25°C ranges from 1mΩ to 6mΩ, and the DC internal resistance (DCR) ranges from 3mΩ to 15mΩ. This effectively suppresses polarization and heat generation during high-rate discharge, achieving a high-power all-tab cylindrical lithium-ion battery and electrical device that balances high rate capability, low temperature rise, and long cycle life.

[0018] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a schematic diagram of a fully tabbed cylindrical lithium-ion battery structure provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of the external structure of a fully tabbed cylindrical lithium-ion battery provided in an embodiment of this disclosure; Figure 3 This is a schematic cross-sectional view of a fully tabbed cylindrical lithium-ion battery provided in an embodiment of this disclosure; Figure 4 This is a schematic diagram of the unfolded structure of a fully tabbed cylindrical lithium-ion battery provided in an embodiment of this disclosure; Figure 5 This is a schematic diagram of the positive electrode of a fully tabbed cylindrical lithium-ion battery cell provided in an embodiment of this disclosure; Figure 6 This is a schematic diagram of the negative electrode sheet of a fully tabbed cylindrical lithium-ion battery cell provided in a disclosed embodiment; Figure 7a This is a schematic diagram of the current path of a monopole structure provided in an embodiment of this disclosure; Figure 7b This is a schematic diagram of the current path of a full-tab structure provided in an embodiment of this disclosure; Figure 8 This is a schematic diagram comparing the surface temperature rise curves of Embodiment 1 and Comparative Example 1 at different discharge rates, provided by the present disclosure. Figure 9 This is a schematic diagram comparing the DCR growth rate of one embodiment and a comparative example after 500 cycles of 1C / 1C, provided by this disclosure.

[0020] Figure label: 1-Cover; 2-End face tab; 3-Cell; 4-Shell; 5-Positive electrode; 6-Negative electrode; 7-Separator; 8-Winding start end; 9-Winding end; 10-Positive active material area; 11-Insulating coating area; 12-Positive tab flattening area; 13-Negative active material area; 14-Negative tab flattening area. Detailed Implementation

[0021] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0022] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0023] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better description of the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this disclosure according to the specific circumstances.

[0024] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0025] Unless otherwise stated, the term "multiple" means two or more.

[0026] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0027] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.

[0029] While all-tab technology has been proposed to reduce tab resistance, there is still a lack of technical solutions specifically designed for the 21650 small-size platform that systematically couple all-tab structural parameters with multi-dimensional electrical performance parameters (such as rate capacity retention, temperature rise coefficient, internal resistance, pulse voltage drop, and cycle DCR growth rate). In particular, thermal management of small-volume batteries at high rates is extremely challenging. Simply reducing internal resistance without simultaneously controlling temperature rise and cycle stability cannot meet the safety and long lifespan requirements of scenarios such as eVTOL.

[0030] In response to the above technical problems, combined with Figures 1 to 6 As shown, this embodiment of the present disclosure provides a fully tabbed cylindrical lithium-ion battery, including a casing 4, a battery cell 3, and a cover 1, wherein the casing 4 and the cover 1 together form an inner cavity, and the battery cell 3 is disposed in the inner cavity. The welding of the battery cell 3 to the casing 4 can be achieved by first fixing the spatial position of the battery cell 3 and the casing 4 with a tooling fixture, then using a press to insert the battery cell 3 into the casing and ensuring reliable contact between the positive terminal face of the battery cell 3 and the lower inner end face of the casing 4, and finally using a laser welding machine to fix the battery cell 3 and the casing 4 together. Further, combined with... Figures 2 to 4 As shown, the battery cell 3 is formed by winding a positive electrode 5, a negative electrode 6, and a separator 7 between them (i.e., from the starting end to the ending end of winding). Its two ends each include a positive electrode tab and a negative electrode copper foil tab. After being flattened and shaped, the positive and negative electrode tabs form end face tabs 2, namely the positive and negative end face tabs. Both the positive and negative end face tabs are welded to the cover 1 structure, and one end of the cover 1 structure is an integral part of the shell 4.

[0031] Specifically, combined Figure 5 and Figure 6As shown, the positive electrode 5 consists of a positive current collector and a positive active material coating applied to at least one of its surfaces, thereby forming a positive active material region, an insulating coating region, and a positive electrode flattening region. The negative electrode 6 consists of a negative current collector and a negative active material coating applied to at least one of its surfaces, thereby forming a negative active material region and a negative electrode flattening region. The positive active material in the positive active material coating is LiNi. x Co y Mn z M j O2, where x ranges from 0.8 to 0.95, y ranges from 0.01 to 0.1, z ranges from 0.01 to 0.1, j ranges from 0 to 0.05, and M includes one or more of aluminum (Al), zirconium (Zr), titanium (Ti), magnesium (Mg), strontium (Sr), yttrium (Y), lanthanum (La), cerium (Ce), and vanadium (V). The nominal capacity of the all-tab cylindrical lithium-ion battery is 3.0 Ah to 5.5 Ah, and the nominal voltage is 3.5 V to 3.7 V. The discharge capacity retention rate of the all-tab cylindrical lithium-ion battery at 25°C at an 8C rate to a cutoff voltage of 2.5 V is greater than or equal to 80%. Furthermore, the maximum surface temperature rise during the 8C continuous discharge process is less than or equal to 40°C. The AC internal resistance (ACIR) of the all-tab cylindrical lithium-ion battery at 25°C ranges from 1 mΩ to 6 mΩ, and the DC internal resistance (DCR) ranges from 3 mΩ to 15 mΩ.

[0032] Optionally, the positive electrode current collector in this application is aluminum foil, with the aluminum foil accounting for 3.5 wt% to 5.3 wt% of the total weight of the all-tab cylindrical lithium-ion battery (a1), and the positive electrode active material coating accounting for 32.1% to 46.7% of the total weight of the all-tab cylindrical lithium-ion battery (a2). Meanwhile, the negative electrode current collector is copper foil, with the copper foil accounting for 6.1 wt% to 13.2 wt% of the total weight of the all-tab cylindrical lithium-ion battery (b1), and the negative electrode coating accounting for 17.4% to 27.5% of the total weight of the battery (b2), and satisfying: 0.016 ≤ (a1... b1) / (a2 b2)≤0.157. In this way, by ensuring that the mass ratio of copper foil, aluminum foil, positive electrode active material coating, and negative electrode active material coating meets certain requirements, the heat dissipation performance of the battery can be improved, the internal heat generation of the battery can be reduced, and thus the high-temperature charge and discharge performance of the battery can be enhanced.

[0033] Optionally, the electrolyte in this application accounts for 8.4% to 17.3% of the total weight of the all-tab cylindrical lithium-ion battery, and the electrolyte injection volume satisfies 1g / Ah to 1.6g / Ah.

[0034] Optionally, the all-tab cylindrical lithium-ion battery of this application is continuously discharged at an 8C rate to a cutoff voltage of 2.5V at an ambient temperature of 25°C, and the surface temperature of the battery does not exceed 80°C during the discharge process.

[0035] Optionally, the discharge capacity retention rate of the all-tab cylindrical lithium-ion battery of this application is greater than or equal to 75% when continuously discharged at 10C rate to the cutoff voltage of 2.5V at 25°C.

[0036] Optionally, the voltage drop of the all-tab cylindrical lithium-ion battery of this application is less than or equal to 0.5V when continuously discharged at a 5C rate for 10s at an ambient temperature of -20℃.

[0037] Optionally, the temperature rise coefficient k of the all-tab cylindrical lithium-ion battery of this application is less than or equal to 5℃ / C, where k=(T 8C -T 0.2C ) / 8, T 8C T represents the surface temperature of the cell at the end of an 8C discharge. 0.2 C represents the surface temperature of the battery cell at the end of a 0.2C discharge. Optionally, the DC internal resistance (DCR) of the all-tab cylindrical lithium-ion battery of this application at 25°C is 3mΩ~10mΩ.

[0038] Optionally, the DC internal resistance (DCR) of the all-tab cylindrical lithium-ion battery of this application is 40mΩ~90mΩ at -20℃. After 500 cycles at 1C / 1C, the DC internal resistance (DCR) growth rate of the all-tab cylindrical lithium-ion battery at 25℃ is less than or equal to 50%.

[0039] Optionally, the maximum continuous discharge current of the all-tab cylindrical lithium-ion battery of this application is greater than or equal to 70A.

[0040] Optionally, the maximum pulse discharge current of the all-tab cylindrical lithium-ion battery of this application is greater than or equal to 200A.

[0041] Optionally, the outer diameter D of the casing of the all-tab cylindrical lithium-ion battery is 20.8mm~21.5mm, and the height of the casing is 64.8mm~65.5mm.

[0042] In another embodiment, the current path of the all-tab cylindrical lithium-ion battery provided in this application is as follows: Figure 7b As shown, the current path of the monopole structure in related technologies (such as...) Figure 7aCompared to the traditional structure (shown by the dashed line), the current in the all-tab structure flows in or out uniformly across the entire flattened end face, shortening the current path by two orders of magnitude. This reduces the current density in the tab region by more than 60%, significantly lowering the battery's ACIR from 8mΩ~12mΩ in the traditional structure to 1mΩ~6mΩ. Meanwhile, the outer diameter D of the all-tab cylindrical lithium-ion battery in this application is 20.8mm~21.5mm, and the height H is 64.8mm~65.5mm. The volume of the casing is calculated using the formula: V=π×(D / 2). 2 ×H, the calculated volume of the shell is approximately 22.0 cm³. 3 ~23.8cm 3 This size allows the battery to achieve a high volumetric power density within a compact space of the same size.

[0043] The following technical effects can be achieved by using the all-tab cylindrical lithium-ion battery provided in this disclosure embodiment: (1) 8C continuous discharge capacity retention rate greater than or equal to 80%: Based on the low internal resistance of ACIR of 1mΩ~6mΩ and DCR of 3mΩ~15mΩ, the full-tab structure makes the current distribution of the electrode highly uniform, significantly reducing concentration polarization and ohmic polarization, ensuring that the capacity is still greater than or equal to 80% at high 8C rates. In contrast, the 8C retention rate of single-tab batteries in related technologies is usually less than 70% due to the concentrated current density at the tab.

[0044] (2) Maximum temperature rise of 8C discharge surface is less than or equal to 40℃: The full tab structure extends the current inlet from a single point to the entire end face, greatly reducing the tab resistance and fundamentally reducing I. 2 The 21650 specification generates R-ohm heat. Meanwhile, compared to the 21700 specification, the 21650 specification has a shorter axial height (64.8mm~65.5mm), resulting in a shorter heat diffusion path within the electrode, allowing heat to be quickly transferred to the casing surface for dissipation. These two factors work together to keep the battery surface temperature rise below 40°C even under continuous high-power discharge at 8C, avoiding the risk of thermal runaway.

[0045] (3) Original temperature rise coefficient k is less than or equal to 5℃ / C: This application introduces a temperature rise coefficient k=(T8C-T 0.2 C / 8 serves as a normalized metric for measuring battery thermal management capabilities. This metric directly reflects the rate of temperature rise caused by each additional unit discharge rate. A k value less than or equal to 5°C / C indicates that the battery has good thermal inertia, and that increasing the discharge rate will not lead to an exponential deterioration in temperature rise, providing a predictable thermal behavior boundary for high-power applications.

[0046] (4) Surface temperature control under extreme high temperature environment: When continuously discharged at 8C rate at an ambient temperature of 25℃, the surface temperature of the battery does not exceed 80℃. This is due to the ultra-low internal resistance and uniform current distribution of the electrode plates brought by the full tab structure, which significantly suppresses polarization heat and ohmic heat during high-rate discharge, so that the battery can still maintain a safe surface temperature under extreme high temperature conditions, meeting the stringent use requirements of closed spaces or high temperature environments.

[0047] (5) At an ambient temperature of -20℃, the voltage drop is less than or equal to 0.5V within 10 seconds of continuous discharge at a 5C rate: The low internal resistance (ACIR as low as 1mΩ~6mΩ) enables the battery to respond quickly and the voltage drop to controllable when dealing with instantaneous high power demands such as eVTOL take-off and landing and rapid acceleration of drones, thus ensuring the stable operation of electrical equipment.

[0048] (6) Wide temperature range and low internal resistance: The battery DCR is 3mΩ~15mΩ at 25℃ and 40mΩ~90mΩ at -20℃, ensuring that the battery still has acceptable power output capability in low temperature environment and meets the starting requirements in cold climate.

[0049] (7) DCR growth rate of less than or equal to 50% after 500 cycles: In related technologies, single-tab batteries are subjected to high current density and high temperature in the tab area for a long time during high-rate cycling. The welding interface between the tab and the current collector is prone to pulverization, and the electrolyte decomposes rapidly at the tab, resulting in rapid DCR growth. The all-tab structure of this application eliminates the hot spot of a single tab, making the current and heat distribution uniform. With a capacity design of 3.0Ah~5.5Ah, the DCR growth rate is controlled within 50% after 500 cycles of 1C / 1C, which is significantly better than the single-tab solution (whose typical DCR growth rate is over 80%).

[0050] (8) High limit output capability: the maximum continuous discharge current is greater than or equal to 70A and the maximum pulse discharge current is greater than or equal to 200A, which are both at the leading level in the industry in terms of continuous power density and pulse power density.

[0051] (9) Optimal balance between size and power density: The outer diameter of the shell is 20.8mm~21.5mm and the height of the shell is 64.8mm~65.5mm, which makes it more adaptable to space-constrained scenarios such as UAVs and eVTOL.

[0052] In addition, this embodiment also provides an electrical device, including a multi-tab cylindrical lithium-ion battery as described in this application.

[0053] The present application will be further explained below with reference to the embodiments and comparative examples. The electrical performance tests of the embodiments and comparative examples were all carried out at 25±2℃, unless otherwise stated.

[0054] Test method description: AC internal resistance (ACIR): Measured using an AC impedance meter at a frequency of 1 kHz and an amplitude of 5 mV.

[0055] DC internal resistance (DCR): The hybrid pulse power characteristic (HPPC) test method is used. The battery is charged to full capacity with a 1C current, left to stand for 1 hour, and then an 8C discharge pulse is applied for 10 seconds. The voltage difference ΔV at the beginning and end of the pulse is recorded. DCR = ΔV / (8C current).

[0056] Rate capacity retention: The reference capacity C was measured at 25°C by discharging at 0.2C to 2.5V. 0.2 Discharge to 2.5V at the target rate (8C or 10C) and measure the capacity C-rate. Retention rate = C-rate / C 0.2 ×100%.

[0057] Surface temperature rise: A type K thermocouple was attached to the geometric center of the side wall of the battery casing, and the highest surface temperature T during the discharge process was recorded. max Temperature rise ΔT = T max -T 环境 .

[0058] Temperature rise coefficient k: k = (T8C - T) 0.2 C) / 8, where T8C and T 0.2 C represents the surface temperature of the cell at the end of 8C and 0.2C discharge, respectively.

[0059] Voltage drop: At an ambient temperature of -20℃ and 100% SOC, a 5C discharge current was applied for 10 seconds, and the voltage drop ΔV = V0 - V was recorded. 10s .

[0060] Cyclic DCR growth rate: After 500 cycles under a 1C / 1C charge / discharge regime, the DCR is measured every 100 cycles using the HPPC method described above. Growth rate = (DCR...) 500 -DCR0) / DCR0×100%.

[0061] Example 1 (Balanced High Power Type) Battery specifications and structural parameters: The outer diameter D of the casing is 21.0 mm, the height H is 65.0 mm, the side wall thickness is 0.22 mm, and the bottom wall thickness is 0.32 mm. The outer diameter of the battery cell is 20.3 mm, and the height is 62.3 mm.

[0062] Electrode and electrolyte: The positive electrode active material is a mixture of lithium nickel manganese cobalt oxide (NCM811) and lithium cobalt oxide (LCO) in a mass ratio of 8:2, with an areal density of 18.0 mg / cm³. 2 The compacted density is 3.2 g / cm³. 3The negative electrode active material in the coating is a composite material of artificial graphite and hard carbon, with hard carbon accounting for 5% by mass and having an areal density of 9.5 mg / cm³. 2 The compacted density is 1.6 g / cm³. 3 The separator is a 9μm thick polyethylene (PE) base membrane coated with a 2μm Al₂O₃ ceramic layer on one side. The electrolyte uses 1.2 mol / L LiPF₆ as the lithium salt, and the solvent is a mixture of ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) in a volume ratio of 2:2:6, with 2wt% LiFSI, 1wt% VC, and 0.5wt% LiODFB added as functional additives. The electrolyte injection coefficient is 1.25 g / Ah.

[0063] Performance parameters and technical effects: (1) According to the test, the nominal capacity of the battery in this embodiment is 4.5Ah and the nominal voltage is 3.65V; (2) ACIR is 3.5mΩ at 25℃; DCR is 8.0mΩ (25℃) and 55mΩ (-20℃); (3) The capacity retention rate during continuous discharge at 8C is 82% (relative to 0.2C); (4) The surface temperature rises to 35°C during the 8C discharge process; (5) Temperature rise coefficient k = (50.5 - 15.3) / 8 = 4.4℃ / C, where 50.5℃ is the temperature of the cell surface at the end of 8C discharge, and the highest temperature rise of the cell surface during non-discharge process; (6) The 10C continuous discharge capacity retention rate is 77%; (7) At an ambient temperature of -20℃, the voltage drop after continuous discharge at a 5C rate for 10s is 0.42V; (8) At an ambient temperature of 25°C, the highest surface temperature of the battery when continuously discharged at an 8C rate is 68°C. (9) The maximum continuous discharge current is 82A, and the maximum pulse discharge current is 225A; (10) After 500 cycles of 1C / 1C, the DCR growth rate is 42%.

[0064] This embodiment achieves 82% capacity retention and only 35°C temperature rise at high 8C discharge rates, based on low internal resistance of 3.5mΩ ACIR and 8.0mΩ DCR. This demonstrates that the synergistic effect of the all-tab structure and high-conductivity electrolyte can effectively suppress polarization and heat generation during high-rate discharge. The 8C discharge surface temperature is only 68°C at 25°C, far below the upper limit requirement of 80°C, exhibiting excellent high-temperature power safety.

[0065] Example 2 (Ultra-High Power Type) The main difference from Example 1 is that the positive electrode active material is NCM811, and the areal density is reduced to 15.0 mg / cm³. 2 (Thinner coating to reduce lithium-ion solid-phase diffusion resistance), compaction density 3.0 g / cm³ 3 The mass percentage of hard carbon in the negative electrode active material coating is increased to 10%, with an areal density of 8.0 mg / cm³. 2 The LiFSI content in the electrolyte was increased to 3wt% to further improve conductivity and low-temperature performance. The cell has an outer diameter of 20.4mm, a height of 62.5mm, and an electrolyte filling coefficient of 1.05g / Ah.

[0066] Performance parameters and technical effects: (1) The nominal capacity is 4.0Ah and the nominal voltage is 3.60V; (2) ACIR is 2.5mΩ; DCR is 5.0mΩ (25℃) and 42mΩ (-20℃); (3) The 8C continuous discharge capacity retention rate is 85%; (4) At an ambient temperature of 25°C, the highest surface temperature of the battery continuously discharged at an 8C rate is 32°C; (5) Temperature rise coefficient k = 4.0℃ / C; (6) 10C continuous discharge capacity retention rate is 80%; (7) At an ambient temperature of -20℃, the voltage drop after continuous discharge at a 5C rate for 10s is 0.35V; (8) The maximum continuous discharge current is 85A (21.25C), and the maximum pulse discharge current is 250A; (9) After 500 cycles of 1C / 1C, the DCR growth rate is 38%.

[0067] This embodiment further reduces the ACIR to 2.5 mΩ by lowering the electrode areal density, increasing the hard carbon ratio, and optimizing the electrolyte. The low internal resistance significantly reduces the polarization heat at 8C rate, with a temperature rise coefficient k of only 4.0 °C / C, demonstrating the technical potential of this application in extreme high-power output scenarios. The 80% 10C retention rate also meets the relevant constraint of ≥75% for this application.

[0068] Example 3 (Wide Temperature Long Cycle Type) The main difference from Example 1 is that the positive electrode active material is NCM622 with an areal density of 20.0 mg / cm³. 2 The negative electrode active material is artificial graphite with an areal density of 10.5 mg / cm³. 2The electrolyte uses 1.2 mol / L LiPF6 as the lithium salt, and the solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 3:3:4. 3 wt% VC, 1.5 wt% FEC, and 1 wt% LiBOB are added as functional additives to balance high-temperature stability and low-temperature conductivity. The electrolyte injection coefficient is 1.20 g / Ah.

[0069] Performance parameters and technical effects: (1) The nominal capacity is 5.0Ah and the nominal voltage is 3.70V; (2) ACIR is 3.6mΩ; DCR is 10.0mΩ (25℃) and 48mΩ (-20℃); (3) The 8C continuous discharge capacity retention rate is 80%; (4) The maximum surface temperature of the 8C discharge is 38℃; (5) Temperature rise coefficient k = 4.8℃ / C; (6) The 10C continuous discharge capacity retention rate is 75%; (7) At an ambient temperature of -20℃, the voltage drop after continuous discharge at a 5C rate for 10s is 0.48V; (8) At an ambient temperature of 25°C, the highest surface temperature of the battery when continuously discharged at an 8C rate is 78°C. (9) The maximum continuous discharge current is 80A, and the maximum pulse discharge current is 250A; (10) After 500 cycles of 1C / 1C, the DCR growth rate is 38%.

[0070] This embodiment focuses on a wide temperature range and long cycle life. By optimizing the electrolyte film-forming additives (FEC, LiBOB), the DCR growth rate after 500 cycles is only 38%. The ACIR is optimized to 3.6mΩ, and combined with the all-tab structure, the battery surface temperature is controlled below 78°C during continuous discharge at 8C rate at an ambient temperature of 25°C, meeting the stringent requirement of not exceeding 80°C in this application. The DCR at -20°C is 48mΩ, falling within a wide temperature range of 40mΩ to 90mΩ, verifying the power output capability of this application in low-temperature environments.

[0071] Example 4 (Low internal resistance boundary verification type) The main difference from Example 1 is that: the positive electrode current collector uses a 12μm thick double-sided bright aluminum foil, and the negative electrode current collector uses a 6μm thick double-sided bright copper foil; the positive electrode surface density is 16.0 mg / cm³. 2 The negative electrode surface density is 8.5 mg / cm³. 2The electrolyte is 1.5 mol / L LiPF6, the solvent is ethylene carbonate (EC) / dimethyl carbonate (DMC) in a volume ratio of 3:7, and 3.5 wt% LiFSI is added as a functional additive. The injection coefficient is 1.35 g / Ah.

[0072] Performance parameters and technical effects: (1) The nominal capacity is 3.5Ah and the nominal voltage is 3.60V; (2) ACIR is 1.8mΩ; DCR is 4.0mΩ (25℃) and 40mΩ (-20℃); (3) The 8C continuous discharge capacity retention rate is 84%; (4) At an ambient temperature of 25°C, the highest surface temperature of the battery continuously discharged at an 8C rate rises to 30°C. (5) Temperature rise coefficient k = 3.8℃ / C; (6) The maximum continuous discharge current is 90A and the maximum pulse discharge current is 280A.

[0073] This embodiment verifies the technical feasibility of the ACIR lower limit of the present application in the lower end of the range of 1mΩ to 6mΩ. Through the synergistic design of ultra-thin current collector, low areal density electrode and high salt concentration electrolyte, the ACIR is reduced to 1.8mΩ, resulting in a temperature rise of only 30°C at 8C, demonstrating excellent high power performance under low internal resistance boundary.

[0074] Comparative Example 1 (Traditional Monopole Structure) Using the same shell size, electrode material formulation, electrolyte and cell geometry as in Example 1, only the full tab structure is replaced with a traditional single tab structure: an aluminum tab with a width of 4mm and a length of 20mm is welded to one edge of the positive electrode, and a nickel tab with a width of 4mm and a length of 20mm is welded to one edge of the negative electrode. The tabs are welded to the cover plate terminals for conduction.

[0075] Performance parameters and technical effects: (1) The nominal capacity is 4.5Ah; (2) The ACIR is 9.5mΩ (171% higher than the 3.5mΩ of Example 1, which does not meet the range of 1mΩ~6mΩ). (3) The DCR is 20mΩ (25℃), which does not meet the range of 3mΩ~15mΩ; (4) The 8C continuous discharge capacity retention rate is only 68% (less than 80%). (5) At an ambient temperature of 25°C, the highest surface temperature of the battery that is continuously discharged at an 8C rate rises to 58°C (exceeding 40°C). (6) Temperature rise coefficient k = (73.2 - 15.3) / 8 = 7.2℃ / C (exceeding 5℃ / C); (7) The 10C continuous discharge capacity retention rate is only 62% (less than 75%). (8) At an ambient temperature of -20℃, the voltage drop after continuous discharge at a 5C rate for 10s is 0.85V (more than 0.5V). (9) After 500 cycles of 1C / 1C, the DCR growth rate is 85% (more than 50%). (10) The maximum continuous discharge current can only reach 45A (less than 70A).

[0076] Comparative Example 1 demonstrates that, with identical material systems and battery dimensions, simply changing the tab structure from a full-tab structure to a single-tab structure causes a comprehensive deterioration in the battery's internal resistance, rate performance, temperature rise control, and cycle life, completely deviating from the technical solution of this application. The current concentration effect of the single-tab structure leads to overheating in the tab region, which is the root cause of the degradation in high-rate performance. ACIR 9.5mΩ is a typical value for traditional single-tab structures, while this application reduces it by more than 60% (to 3.5mΩ) through a full-tab structure, which is a structural prerequisite for achieving all high-power performance indicators.

[0077] Comparative Example 2 (High Internal Resistance Type) The same all-tab structure and shell size as in Example 1 are used, but the positive electrode active material is only produced using the NCM811 high-compaction method (area density 24 mg / cm³). 2 Compacted density 3.6 g / cm³ 3 Furthermore, a conventional electrolyte system is used, with the solute being 1.0 mol / L LiPF6 and the solvent being ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 3:7. The system does not contain low-impedance functional additives such as LiFSI.

[0078] Performance parameters and technical effects: (1) The nominal capacity is 4.8Ah; (2) ACIR is 7.5mΩ (not in the range of 1mΩ~6mΩ); (3) DCR is 16mΩ (25℃) (exceeding the upper limit of 15mΩ); (4) The 8C continuous discharge capacity retention rate is 73% (less than 80%). (5) At an ambient temperature of 25°C, the highest surface temperature of the battery that is continuously discharged at an 8C rate rises to 48°C (exceeding 40°C). (6) At an ambient temperature of -20℃, the voltage drop after continuous discharge at a 5C rate for 10s is 0.72V (more than 0.5V). (7) Temperature rise coefficient k = 6.0℃ / C; (8) The maximum continuous discharge current is 65A.

[0079] Comparative Example 2 demonstrates that even with a full-tab structure, if the electrode areal density is too high and the electrolyte conductivity is insufficient, causing the ACIR and DCR to fail to meet the technical requirements of 1mΩ~6mΩ and 3mΩ~15mΩ as specified in this application, the battery still cannot simultaneously meet the technical requirements of 8C capacity retention greater than or equal to 80% and temperature rise less than or equal to 40℃. This indicates that a full-tab structure is only a necessary condition; the key to achieving high power performance lies in combining a low areal density design with an optimized electrolyte system to ensure that the internal resistance falls within a specific range.

[0080] Comparative Example 3 (Cyclic DCR Growth Too Rapid Type) The same all-tab structure, shell size, and electrode formulation as in Example 1 were used, but a conventional electrolyte system was adopted, with 1.2 mol / L LiPF6 as the solute and ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) as the solvent in a volume ratio of 3:7. This electrolyte did not contain any SEI film-forming additives such as VC or LiODFB, and consisted only of lithium salt and carbonate solvent.

[0081] Performance parameters and technical effects: (1) The nominal capacity is 4.5Ah; (2) The initial ACIR is 3.6 mΩ and the initial DCR is 8.2 mΩ (the initial values ​​are consistent with the scope of this application). (3) The 8C continuous discharge capacity retention rate was 81%; (4) At an ambient temperature of 25°C, the highest surface temperature of the battery continuously discharged at an 8C rate rises to 36°C. (5) After 500 cycles of 1C / 1C, the DCR growth rate is 68% (more than 50%). (6) The maximum continuous discharge current is 75A.

[0082] Comparative Example 3 demonstrates that even if the all-tab structure and initial internal resistance meet the requirements of this application, without an effective SEI film formation and interface stabilization mechanism, the active material and electrolyte interface will continue to undergo side reactions during cycling, causing the DCR to increase significantly to 68% after 500 cycles, exceeding the cycling stability boundary of less than or equal to 50% in the technical solution of this application. This indicates that the cycle DCR growth rate is a key lifetime indicator that distinguishes this application from the solution that "only has high initial power but insufficient lifetime".

[0083] The key parameters and technical effects of the above embodiments and comparative examples are summarized in Tables 1 and 2 below: Table 1

[0084] Table 2

[0085] Combination Figure 8 and Figure 9 As shown, the following conclusions can be drawn from the analysis: Examples 1-4 fully meet all parameter constraints of this application: ACIR of 1mΩ~6mΩ, DCR of 3mΩ~15mΩ, 8C retention rate ≥80%, maximum surface temperature rise during 8C discharge ≤40℃, k≤5℃ / C, voltage drop ≤0.5V after continuous discharge at 5C rate for 10s at -20℃ ambient temperature, and DCR growth rate ≤50% over 500 cycles. Through a full-tab structure to reduce internal resistance, and combined with differentiated electrode areal density and electrolyte system, they achieve a balance between high power, low temperature rise, and long lifespan within a capacity range of 3.0Ah~5.5Ah. Example 4 exhibits an ACIR as low as 1.8mΩ, verifying the excellent performance near the lower limit of this application.

[0086] Although Comparative Example 1 (traditional monopole) has the same size and material as Example 1, the internal resistance exceeds the standard due to structural differences, which in turn causes all performance indicators such as 8C retention rate, temperature rise, pulse voltage drop, and cycle life to deteriorate. This proves that the monopole structure and the ACIR constraint of 1mΩ~6mΩ in this application are indispensable.

[0087] Comparative Example 2 (full tab but high internal resistance) shows that having only a full tab structure without low internal resistance materials / electrolytes still cannot fall into the performance space of this application, proving that internal resistance parameters (ACIR, DCR) are the key quantitative bridge for the transformation from structure to performance in this application.

[0088] Comparative Example 3 (all tabs and qualified initial internal resistance, but without SEI additive) illustrates that the cycle DCR growth rate of ≤50% in this application is an important constraint on the long-term reliability of the battery, preventing pseudo-high-power schemes that "meet initial performance standards but rapidly degrade".

[0089] The above comparison fully verifies that the various parameters of this application do not exist in isolation, but are jointly constructed through cross-dimensional coupling of full-tab structure, low internal resistance design, thermal management optimization and interface stability guarantee, which together form a high-power, low-heat and long-life technical solution for 21650 batteries on a small-size platform.

[0090] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A cylindrical lithium-ion battery with multiple tabs, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode is composed of a positive current collector and a positive active material coating applied to at least one surface thereon, and the negative electrode is composed of a negative current collector and a negative active material coating applied to at least one surface thereon, characterized in that, The positive electrode active material in the positive electrode active material coating is LiNi. x Co y Mn z M j O2, wherein the value of x ranges from 0.8 to 0.95, the value of y ranges from 0.01 to 0.1, the value of z ranges from 0.01 to 0.1, the value of j ranges from 0 to 0.05, and x+y+z+j=1, and M includes one or more of aluminum (Al), zirconium (Zr), titanium (Ti), magnesium (Mg), strontium (Sr), yttrium (Y), lanthanum (La), cerium (Ce), and vanadium (V); The nominal capacity of the full-tab cylindrical lithium-ion battery is 3.0Ah~5.5Ah, and the nominal voltage is 3.5V~3.7V; The full-tab cylindrical lithium-ion battery retains a discharge capacity of greater than or equal to 80% when continuously discharged at 8C rate to a cutoff voltage of 2.5V at 25°C; and the maximum surface temperature rise during the 8C continuous discharge process is less than or equal to 40°C. The total tab cylindrical lithium-ion battery has an AC internal resistance (ACIR) ranging from 1 mΩ to 6 mΩ at 25°C and a DC internal resistance (DCR) ranging from 3 mΩ to 15 mΩ.

2. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The positive electrode current collector is aluminum foil, and the proportion (a1) of the aluminum foil to the total weight of the all-tab cylindrical lithium-ion battery is 3.5wt%~5.3wt%. The proportion (a2) of the positive electrode active material coating to the total weight of the all-tab cylindrical lithium-ion battery is 32.1%~46.7%. The negative electrode current collector is copper foil, and the proportion (b1) of the copper foil to the total weight of the all-tab cylindrical lithium-ion battery is 6.1wt%~13.2wt%. The proportion (b2) of the negative electrode coating to the total weight of the battery is 17.4%~27.5%, and satisfies: 0.016≤(a1) b1) / (a2 b2)≤0.

157.

3. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The electrolyte accounts for 8.4% to 17.3% of the total weight of the all-tab cylindrical lithium-ion battery, and the electrolyte injection volume meets the requirement of 1g / Ah to 1.6g / Ah.

4. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The all-tab cylindrical lithium-ion battery is continuously discharged at an 8C rate to a cutoff voltage of 2.5V at an ambient temperature of 25°C, and the surface temperature of the battery does not exceed 80°C during the discharge process. The full-tab cylindrical lithium-ion battery retains a discharge capacity of greater than or equal to 75% when continuously discharged at 10C rate to a cutoff voltage of 2.5V at 25°C.

5. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The voltage drop of the all-tab cylindrical lithium-ion battery is less than or equal to 0.5V when continuously discharged at a 5C rate for 10 seconds at an ambient temperature of -20℃.

6. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The temperature rise coefficient k of the all-tab cylindrical lithium-ion battery is less than or equal to 5℃ / C, where k = (T 8C -T 0.2C ) / 8, T 8C T represents the surface temperature of the cell at the end of an 8C discharge. 0.2C The surface temperature of the cell at the end of a 0.2C discharge.

7. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The DC internal resistance (DCR) of the all-tab cylindrical lithium-ion battery at 25°C is 3mΩ~10mΩ. The DC internal resistance (DCR) of the all-tab cylindrical lithium-ion battery at -20℃ is 40mΩ~90mΩ; After 500 cycles at 1C / 1C, the DC internal resistance (DCR) growth rate of the all-tab cylindrical lithium-ion battery at 25°C is less than or equal to 50%.

8. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The maximum continuous discharge current of the all-tab cylindrical lithium-ion battery is greater than or equal to 70A. The maximum pulse discharge current of the all-tab cylindrical lithium-ion battery is greater than or equal to 200A.

9. The all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The outer diameter of the casing of the full-tab cylindrical lithium-ion battery is 20.8mm~21.5mm, and the height of the casing is 64.8mm~65.5mm.

10. An electrical device, characterized in that, Including the all-tab cylindrical lithium-ion battery as described in any one of claims 1 to 9.

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